Portable desk



FIG. 1 is a perspective view of a portable desk, showing my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a left side elevational view, the right side being a mirror image thereof;

FIG. 4 is a front elevational view thereof; and,

FIG. 5 is a rear elevational view thereof.

FIGS. 2-5 have been drawn on a reduced scale with respect to FIG. 1. 

The ornamental design for a portable desk, as shown and described. 